Cyclone External Combustion Engines and DARPA Self-Fueling Robots

Cyclone Green Revolution Engine can burn any fuel and use any heat source (even focused sunlight) The Schoell cycle engine is a cross between a Rankine, Diesel and Carnot cycle engine.

Rankine cycle is sometimes referred to as a practical Carnot cycle as, when an efficient turbine is used, the TS diagram will begin to resemble the Carnot cycle. The main difference is that a pump is used to pressurize liquid instead of gas. This requires about 100 times less energy than that compressing a gas in a compressor (as in the Carnot cycle). The efficiency of a Rankine cycle is usually limited by the working fluid.

DARPA Using It to Power A Self-refueling Autonomous Robot
H/T to Alfin: Alfin notes that DARPA will be using the cyclone engine to power an autonomous robot.

The purpose of the Energetically Autonomous Tactical Robot (EATR)(patent pending) project is to develop and demonstrate an autonomous robotic platform able to perform long-range, long-endurance missions without the need for manual or conventional re-fueling, which would otherwise preclude the ability of the robot to perform such missions. The system obtains its energy by foraging – engaging in biologically-inspired, organism-like, energy-harvesting behavior which is the equivalent of eating. It can find, ingest, and extract energy from biomass in the environment (and other organically-based energy sources), as well as use conventional and alternative fuels (such as gasoline, heavy fuel, kerosene, diesel, propane, coal, cooking oil, and solar) when suitable.

Here is a presentation on the DARPA long duration robot plans.

Some Cyclone Engine Details

Unlike IC (Internal combustion – regular gase engines) engines, the Cyclone engine uses an external combustion chamber to heat a separate working fluid, de-ionized water, which expands to create mechanical energy by moving pistons or a turbine.

Since the combustion is external to the mechanism, the Cyclone engine can run on any fuel… liquid or gaseous. Ethanol, diesel, gasoline, biomass … anything from municipal trash and agricultural waste to traditional fossil fuels can power the Green Revolution Engine – individually, or in combination. Initial tests of the engine used fuels derived from orange peels, palm oil, cottonseed oil, and chicken fat … none of which are impacted by cartels, hostile governments or dwindling reserves.

Whereas almost anything can go into a Green Revolution Engine, almost nothing comes out. It is exceptionally environment-friendly because the combustion is continuous and more easily regulated for temperature, oxidizers and fuel amount. Lower combustion temperatures and pressures create less toxic and exotic exhaust gases.

Waste Heat Engine
Cyclone’s Waste Heat Engine (WHE, pronounced “we”) is a low temperature, low pressure, self-starting model of the Cyclone Engine.

Some Specs:
6-cylinder radial – uniflow – Rankine cycle engine
Weight 18 lbs without condenser and alternator

Because the WHE runs on heat as low as 225 degrees, it can pull its power from many different sources of “wasted” heat or renewable fuels, such as:

* Commercial or small-scale industrial ovens or furnaces
* Concentrating solar thermal collectors
* Engine exhaust – transportation or power generation
* Biomass combustion – dry and raw waste disposal

Running the Cyclone Engine Without Air for Underwater and Space Applications
Another technological achievement involves running the patented Cyclone Engine by the combustion of an environmentally friendly monopropellant called Moden Fuel. Moden Fuel is able to burn in the complete absence of air, a requirement for underwater and space applications.

Light Weight and Simple

The Cyclone Engine is smaller, with fewer parts. However, the materials handling the high operating temperatures and pressures are slightly more expensive. For example, aluminum block costs a bit more but is much lighter than traditional engine blocks. A typical 4 cylinder block weighs approximately 200 lbs where a Cyclone aluminum block will weigh about 35 lbs with no cores.

The cost of manufacturing the Cyclone Engine should be no more expensive to produce at similar economies of scale than conventional gasoline engines of comparable power output with the advantages of being able to use the least expensive fuel available.

Making Biofuel More Affordable

Ethanol or biodiesel can be burned in pure form in the Cyclone Engine, and does not need to be blended with petroleum based fuels. Furthermore, and more importantly, neither ethanol nor biodiesel needs to be as carefully refined as now, and it does not need to meet narrow specifications. Our preliminary estimate is that eliminating the last few refining steps from the production process of either ethanol or biodiesel would reduce their production cost by 20% to 40%. That would be enough to make them cost competitive with oil, and without subsidies. Because the fuel needed in the Cyclone engine can be much broader in its required specifications it may be possible to come up with production processes that are completely new and which could drop total production costs by 40% to 50% over current methods and processes. It will have the even further benefit of allowing additional biomass feedstocks to be considered than is presently the case.

Efficiency of the Cyclone Engine

Existing high compression uniflow type engines have been built. Water rate determines the efficiency. The use of supercritical & heat regenerative greatly increase the total efficiency. A gasoline engine is about 25% efficient and will use about HP X .08 = gallons per HP per Hour. Diesel about 30-38% and will use approximately HP X .055 = gallons per HP per Hour. The cost of Diesel fuel is approximately 15% more than regular gasoline.

The Mark IV cyclone engine is in the diesel range. However, Cyclone engines well to wheel efficiency is higher as there is no transmission, no filters and other hardware to operate. In stop and go traffic the Cyclone Engine will get far better mileage. The mark II is on the upper scale of gasoline and is less than the Mark IV. Because of a simpler valve mechanism that will lower the cost of Mfg it works at lower temperatures.

Different Engine Models and Applications
The different engine models are described here along with specifications.

1. Small electrical generators in the 1 kW to 10 kW output range. This would be the smallest practical scale of Cyclone Engine. Being relatively light, compact and clean running, this engine/generator package is ideal for household, marine, truck and emergency applications. Can also be used as engines for lawnmowers or other small equipment.

2. Medium size Cyclones of 100 horsepower to 400 horsepower are ideal for passenger automobiles, light trucks and small boats.

3. Large Cyclones from 400 to 1,000 horsepower will target the diesel truck market. These will run well because of the high torque of the Cyclone, not to mention the health and environmental benefits from operating low pollution engines.

4. Refrigeration units could be directly run off the small Schoell Cycle Cyclone Engine. Yachts and commercial craft would benefit greatly because of the lack of smoke and vibration in these engines of 400 to 1000 horsepower.

5. Larger yachts and stand-by generators, i.e. hospitals, will benefit by the absence of vibration, noise and in Cyclone Engines of between 1,000 to 4,000 horsepower.

6. The Cyclone Engine could effectively power light Rail Commuter Trains and large road transporters, as this system is quick to start- up. Such a simple traction engine is far less costly than the large diesel-electric prime-mover engines.

Fox News Video

There is a 4 minute video at Engineering TV

Peswiki has collected information on this company and their engines.

Schoell cycle engine is a cross between a Rankine, Diesel and Carnot cycle engine.

Advent Power Systems – Employing the environmentally friendly external combustion Cyclone Technology engine and associative technologies for the U.S. Military, for biomass production of energy, and related areas which provide superior and cost saving capabilities to Advent Power Systems clients.

Wikipedia covers thermodynamic cycles and the many different kinds of engines.